Food contains three sources of energy: proteins, carbohydrates and fats. Together they supply your body with energy and the tools needed for cell metabolism and replacement. All three are necessary for your body, but some diets stress eating one type of energy source over another. Each contains calories; when you take in fewer calories than your body uses in a day, you lose weight.
Carbohydrates, which contain 4 calories in 1 gram, supply the bulk of the energy needed to keep your body fueled. When carbohydrates aren’t available, your body breaks down fats or protein for energy, but carbohydrates are the quickest energy source. Protein, which also supplies 4 calories per gram, heals damaged tissue and builds new cells, while fats, which supply 9 calories per gram, synthesize hormones and also supply energy. Fats are the most efficient energy source but the slowest to break down.
For an average 2,000-calorie balanced diet, people normally take in 60 grams of protein. The daily recommended intake of fat is 30 percent of your daily calorie intake, or less than 90 grams, with saturated fats and trans fats kept to less than 10 percent of your total intake. Between 50 and 55 percent of your daily calories intake is allotted to carbohydrates in a balanced diet. In any diet, you need protein to maintain tissue and muscle. If you don’t get enough protein, your muscle will break down to supply protein.
The amount of fat and carbohydrate you eat on a diet depends on the number of calories you’re eating. If you’re eating 1,500 calories per day on a balanced diet, you need around 800 calories, or around 200 grams, from carbohydrates and about 500 calories, or 55 grams, from fat.
Low-Carb and Low-Fat Diets
If you follow a low-carbohydrate diet, you typically lower your daily intake to between 50 and 150 grams of carbohydrates per day. Some low-carbohydrate diets, such as the Atkins diet, recommend even fewer carbohydrates per day, starting with 20 grams per day in the first week and moving up in 5-gram increments until you find the maximum number of carbohydrates you can eat without gaining weight. The Zone Diet changes the daily percentages to 40 percent carbohydrates, 30 percent proteins and fats, or around 150 grams of carbohydrates, making it a low-carbohydrate diet. Low-fat diets often recommend dropping fat down to 10 to 20 percent of your daily intake, to between 150 and 300 calories or between 17 and 33 grams per day.
Low-fat diets can deprive your body of some vitamins that are carried in fat. When women eat too little fat, they stop having normal menstrual periods. Binging also becomes more likely if your fat intake drops below 25 percent. Low-carbohydrate diets, on the other hand, may supply too much saturated fat, which could increase your risk of heart disease and some cancers. Follow any unbalanced dieting plan only with your doctor's approval.
- Merck Manual:Carbohydrates, Fats and Proteinsrel="nofollow"
- Centers for Disease Control and Prevention: Carbohydratesrel="nofollow"
- Ask the Dietician: Low Fat Eating Tipsrel="nofollow"
- EveryDiet: Ornish Dietrel="nofollow"
- Atkins Diet & Low Carbohydrate Weight-Loss Support: The zonerel="nofollow"
- Atkins Diet & Low Carbohydrate Weight-Loss Support: Atkins Dietrel="nofollow"
- Goodshoot/Goodshoot/Getty Images
This article reflects the views of the writer and does not necessarily reflect the views of Jillian Michaels or JillianMichaels.com.